1. Field of the Invention
The present invention relates generally to forming of honeycomb core and, more specifically, to computer-controlled tooling capable of providing an adjustable three dimensional surface for forming honeycomb core articles with the capability of applying or directing heated air or gas through the honeycomb core cells as well as providing rapid contour changes. The mechanism of the invention is comprised of a plurality of assembled modules which act in concert with one another to effect the work operation.
2. Description of the Prior Art
Forming of honeycomb core is generally limited to the aerospace industry where a large number of honeycomb core details are used to build contoured, strong, highly weight-efficient structures. In the aerospace industry, each aircraft, or spacecraft, requires many pieces of formed honeycomb core, and the number of formed details is large relative to the amount of planes produced for a given year. A process that can quickly and easily adapt to produce small quantities each of many different details therefore is well-suited to the aerospace industry. Similarly, other aerospace-related components which utilize hot-forming techniques or presses are candidates for the apparatus and method described herein. Within the aerospace industry, matched-die forming tools may be used to fabricate sheet metal and thermoplastic parts. Of the two, thermoplastic sheets can be contour-formed using the described invention if the forming temperatures are within the thermal limit of the tools"" design. Thin gage aluminum sheet metal details could also be formed using this process, although the quality of the resulting parts may not be as high as with present processes.
Other industries in addition to the aerospace industry that need to hold, form, or inspect contoured components can benefit from the described discrete modular approach as well. The modular approach can also be used to translate a series of sensors for rapidly digitizing the surface(s) of a contoured part or component by replacing the pin tips with tips specially-configured to hold sensors or other devices. The digitized data can be directly stored in computer memory for a three-dimensional surface description which can be used by a computer-graphic or numerical control software application. Modular construction adds the ability to isolate and rapidly replace malfunctioning elements by replacing entire modules with spare, off-the-shelf modules. Further repairs can then be implemented off-line. This minimizes down time, and replacement cost. The ability to reconfigure an entire assembly of modules by adding or subtracting modules gives a high degree of versatility from which other forming processes might also benefit.
A pair of patents can be said to be generally representative of the present state of the art of forming complex metal shapes. A first instance is U.S. Pat. No. 4,212,188 to Pinson which discloses a plurality of longitudinally and laterally spaced and opposed die members in a matrix array for engaging and forming a sheet metal article interposed between them. Another instance is U.S. Pat. No. 5,546,784 to Haas et al. which discloses a computer controlled self adjusting sheet metal forming die which can provide rapid contour changes and comprises a computer control device which sends appropriately timed signals to translate each contour element so that a three dimension surface is formed by a discrete matrix of individual pins which press the sheet metal against a forming surface. These inventions, however, are directed to the forming of sheet metal, and do not provide for self-heating. In order to form honeycomb core, new and non-obvious methods and hardware are required.
It was with knowledge of the foregoing state of the technology that the present invention has been conceived and is now reduced to practice.
According to the invention, a die and a stationary member of resilient gas permeable composition are adapted to receive between them a three-dimensional honeycomb core article. The die includes an array of elongated mutually parallel translating pins, each terminating at a tip end and arranged in a matrix for longitudinal movement between retracted and extended positions. The stationary member includes a receiving surface facing and laterally coextensive with the tip ends of the translating pins. The tip ends are engageable with a first end surface of the article, the receiving surface of the stationary member being engageable with a second end surface of the article. The die includes a housing movably mounting the translating pins, drive output shafts drivingly connected with each associated translating pin, a transmission for independent driving controllable interconnection of each translating pin, and a selectively energizable controller interconnecting each transmission to thereby achieve selective rotation of at least one translating pin. Each translating pin may be hollow and have planar sides which prevents its rotation by the restraining action of adjacent translating pins. A controller individually moves the translating pins in a coordinated manner into engagement with the first end surface to thereby impart a desired contour while simultaneously urging the second end surface of the honeycomb core article into engagement with the receiving surface of the stationary member producing a contour substantially similar to the first end surface. Temperature controlled circuitous gas flow may be provided through the translating pins, article, and stationary member.
The present invention details a single-die reconfigirable approach to forming honeycomb core using a modularized, computer-controlled forming die. The forming die utilizes an array of pins or members which translate to form a three-dimensional male or female external surface. The adjustable form die is configured so that hot air is blown through (or between) the discrete pins and through (or into) the cells of the honeycomb core to be formed. The opposite face of the honeycomb core is contacted by porous material to facilitate the flow of hot air or gas through the cells of the honeycomb core. Conformable material, material which the core cells can penetrate without cell-wall damage, or a fluid-filled bladder react the forming forces received by the honeycomb core. The described invention allows the forming sequence and core deformation to be controlled using press forming techniques in combination with partial and/or complete translation of the translating pills.
The present invention provides numerous advantages over the prior art including:
greater versatility: contour changes are made by recalling files from computer memory;
adaptability to changes: stored data can be xe2x80x9ctweakedxe2x80x9d as needed by changing pin translational data;
lower space requirements: no extra dies need to be stored;
greater production output;
less down time for contour changes; and
lower overall tooling cost which results from using the described adjustable, discrete heated forming process compared to presently-used fixed-die forming systems when a variety of core shapes must be formed by the same forming machine or system.
The process described herein is also inherently safer to the honeycomb core and to personnel since groups of pins can be used for intermediate core clamping to control local strains, and heavy fixed contour dies do not have to be changed with each different core shape needed.
When forming a wide-enough variety of honeycomb core shapes that it is advantageous to use a discrete, adjustable form die method over the typical heated core-and-fixed-die method, a modular approach to building larger form dies can offer a lower overall system cost than a non-modular approach. When many modules are assembled in a xe2x80x9cbuilding blockxe2x80x9d approach, lower overall cost is achieved by simplifying wiring, assembly, and machining operations. Inherently lower overall risk is also associated with modulalization because this approach reduces the magnitude of errors which cause scrap when creating larger-scale tools. Lower risk in this case translates to lower overall cost. A more consistent and accurately formed core contour can also result from the better temperature control and method of applying and removing heat as needed, and not before.
Easier servicing, component replacement, and less down time result when using the modular xe2x80x9cbuilding blockxe2x80x9d approach described herein. Individual modules utilize quick-disconnect electrical plugs, and rapid cross shaft gearing connections so that module replacement can be accomplished with minimum down time. Individual module repair and/or service can then take place off-line.
Still greater versatility can be achieved by inexpensively allowing overall tool plan form size changes. The overall plan form (length and width) dimensions of the active forminig area can be changed when using the modular xe2x80x9cbuilding blockxe2x80x9d units to create adjustable form tools. Modules can easily be added or subtracted within the limitations allowed by the overall form tool base plates. The base plates can have printed circuitry, electrical connectors, pre-installed wiring, and/or bus bars for motor power, logic, and communication between modules and between modules and computer(s), all using common parts to lower assembly time and cost.
Framing members, if used, around the die assembly may have to be changed, but their cost would be low compared to replacement of an entire form tool of larger plan form, that is, overall length and width.
This invention can also claim all of the advantages of adjustable tooling. Many fixed-contour dies can be replaced by the adjustable dies described herein. This represents a significant tooling savings as well as savings in storage space, handling, repair, maintenance and rework of fixed dies.
Further, the invention described herein can be used for room temperature honeycomb core forming of aluminum honeycomb core, for example, as well as hot forming of Nomex(trademark), graphite, fiberglass, and other nonmetallic honeycomb. The described hardware can also be used to retrofit old fixed-die presses.
Other and further features, advantages, and benefits of the invention will become apparent in the following description taken in conjunction with the following drawings. It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory but are not to be restrictive of the invention. The accompanying drawings which are incorporated in and constitute a part of this invention, illustrate one of the embodiments of the invention, and together with the description, serve to explain the principles of the invention in general terms. Like numerals refer to like parts throughout the disclosure.